WP_Tax_Query::get_sql_for_query()
Method: Generates SQL clauses for a single query array.
Source: wp-includes/class-wp-tax-query.php:302
WP_Tax_Query::get_sql_for_clause()
Method: Generates SQL JOIN and WHERE clauses for a “first-order” query clause.
Source: wp-includes/class-wp-tax-query.php:384